Temperature control apparatus for turbine cases



April 10, 1962 D. J. BUCKINGHAM TEMPERATURE CONTROL APPARATUS FORTURBINE CASES Filed July l, 1959 2 Sheets-Sheet 1 MMM) AT-roRNEYS April10, 1962 D. E. J, BUCKINGHAM 3,029,064

TEMPERATURE CONTROL APPARATUS FOR TURBINE CASES Filed July 1, 1959 2Sheets-Sheet 2 INVENTOQ DAVID E dBucmN-mm BY I V uw, f 93,4% M

ATTORNEYS Y 3,029,364 TEMXBERATURE CONTROL APPARATUS FOR 'EURBlNE CASESlY David Edwin .lames Buckingham, Loudon, England, as-

signor to D. Napier s Son Limited, London, England, a company of GreatBritain A Filed July 1, 1959, Ser. No. 824,264 Claims priority,application Great Britain July 11, 1953 a Claims. (Cl. 253-39.1)

This invention relates to apparatus for controlling the temperature ofthe casing of a turbine employing hot Working r'iuid and moreparticularly of a combustion turbine.

One of the requirements if a turbine is to have high efficiency is thatthe blade tip clearance, -that'is to say the clearance between the tipsof the rotor blades and the surrounding casing, should be maintained assmalles possible. Allowance has to be made, however, for differentialthermal expansion between the parts of the rotary assembly and thecasing and also for distortion which may occur due to temperaturedifferences at different circumferential points around the casing.

Various proposals have been made to provide air cooling for the turbinecasing by providing a cooling charti-y ber or series ot' cooling airchambers extending circumferentially around the casing and means forcausing the air ow through such chamber or chambers, such cham-y ber orchambers usually being formed within the appropriate part of the outermain wall of the casing by a so-called shroud ring assembly, which maybein one piece or built up from a series of sections, and lies' a'd`jacent to the blade tips. For convenience in the present specification,therefore, the turbinel casing will be rei garded as including any suchshroud ring assemblyv or similar parts which form the cooling chamber orcharnbers or a part or parts of such chamber or chambers.

Apparatus according to the present invention for controlling thetemperature of the casing of a turbine entpioying a hot uid andincluding at least o'ne'cooling air chamber extending circumferentiallyof the casing, comprises means for controlling the ow of cooling airthrough said cooling air chamber at least one temperature-re# sponsivedevice arranged'to be responsive to temperature changes in the part ofthe casing adjacent to the cooling air chamber, and control meanscontrolled by said temperatureeresponsive device and arranged to controlthe cooling air flow through the said chamber and'hence the temperatureof the said part of the turbine casing.

Preferably the turbine casing comprises a series of cooling air chambersdisposed circumferentially around the casing, two or more cooling airpassages each arranged so that `the cooling air flowing through any oneof them ilows also through one or more ofthe cooling air cham- I berswhich extend around a sectiononly of the circumterence of the casing andtwo or moretemperature-responsive devices each arranged to be-responsiveto the temperature of the part of the casing constituting a section onlyoi the circumference of the casing and to conA trol the air iiow throughthe cooling air passage associated with the chamber or chambersextending around that section.

The apparatus in this form thus provides for the separate control inaccordance with requirements of the temperature of each of two or moreangularly displaced cir curnterential parts or sections of the turbinecasing and thus tends to ensure not only against undesirable difierencesin the mean thermal expansion respectively of the casing and the bladescausing undesirable changes in the mean tip clearance of the blades, butalso tending to ensure against any local distortion of the casing suchas would alter locally the tip clearance of the blade with- "icc 2 outnecessarily materially"r aiecting the mean tip clear'- ance.

Preferably in the'arangetnent employing tvvo or more cooling airpassages referred to' above these passages constitute deliverypassages'by' which cooling air is' dc'- liv`e1'ed, for example fromtheair-compressing' part of` the combustion turbine, and the controlniean's'comprise throttle valves arranged respectively in such passagesand each controlled b'y the appropriate temperature-responsive device.

The form of te'xripera'turel'responsive devices' used and theirarrangement in' accordance' with thepreser'it in'- venti'on may varyconsiderably bntone a'rrang'erneutv according to the invention ist'shown' by Way' of eiiainple, andpartly diagrammatically, in thea'c'compayingdawings, in which f FIGURE l` isa' somewhatdiagrammatic'cross-section of a turbine ca'singin'aplae normal to theaxis of ,the casing and atl a' point inthe lerigthof the casing'atwhichin the assembledtrbine'it will intersect one of the'discs carryingajring' 'of rotor blades.4

FIGURE 2 is anenla'r'g'ed View from the saine direc'- tion as" FIGURE 1of 'one' oftheA valve assemblies and its assciated'pai'ts as used 'inthe construction shown in Fidonet, y

FIGURES' isV anA underneath plan view partly in section of thevalv'eassembly'shovvn in FIGURE 2, and

VlftGlfllE 4' is a cross-'sectionon' the line IVe-IV of FIGURE 2; ,l

With the arrangement somewhatv diagrammatically shown in FIGURE 1 theturbine'casingds formed to provide opposite the tips of a ring ofn'rotorblades a donble'- walledcasing 1- constituting in` effect an air-cooledShroud ring comprisinga series of airV coolingchambers 2, 3, 4,5,-:6,.7' disposed'circumferentially aroundthe casi-ngfas shown sothat'each chamber 'extends-around' a par-t of the' circumference of thecasing.- It isl to be understood `that the` construction embodying theseries'orr circuirtferentiallyA disposed `chambers is onlydiagrammatically shown in FIGURE l for convenience since the details ofconstruction of the casing to' provide the'circumferentially extendingchambers in itselfH constitutes no part of the invention.I v

Arranged at equal circumferential'intervalsaroundf'the casing are Vsixvalve assemblies each indicated generally in- FIGURE 1 -by the referencenumeral 8, eachvvalve assembly 8 having a cooling air: inlet passageindicated :it-9 to which-cooling aircan be supplied in known mannerfromany convenient sourceV ofcooling. air such as an appropriate stage inthe compressor of the turbine of a forwardly facing air inlet-on anaircraftin whichthe turbine is installed, andan air-delivery passagelllfleading-from the valve assembly into one end'rofr one of theadjacent cooling airchambers 2v to 7i The'other end of each of theseychambers 2 to 7`- communicates withran outlet passage 1-1v by which-thecooling'air 'escapes from the chamber and maybe ledfin `known manneryintofthe working chamber of the turbine so as to pass away with theworking tluid.

Associated with each of the valve assemblies and arranged to operate thevalves of such assemblies in a manner more fully described hereafter, isa steel band 12 which extends from a'pin 13, 13a, 13b, 13C, 13d, 13e onits associated valve assembly, around an arc of the casing 1 such thatit lies in contact with the outer wall of the casing over a substantialpart ofthe circumferential length of one of the cooling air chambers 2,to 7 and also over a substantial part of the circumferential length ofthe next adjacent cooling air chamber. Thus in the arrangement shown inFIGURE 1 the bands extend respectively from the pin 13 to an anchoringpin 14 on the casing, from the pin 13a to an anchoring pin 14a on thecasing, from the pin 13b to lan anchoring pin 14b on the casing, fromthe pin 13C to an anchoring pin 14e on the casing, from the pin 13d tothe anchoring pin 14d on the casing, and from the pin13e` to theanchoring pin 14e on the casing.

The casing is assumed to be formed of aluminum alloy or magnesium alloyand under the influence of temperature changes due to different workingconditions therefore expands and contracts to a greater degree than thesteel bands 12. The relative expansion and contraction of the bands andthe casing which thus occurs is used to operate the valves (hereinaftermore fully described) in the valve assemblies 8.

To this end each valve assembly, as shown in FIG- URES 2, 3 and 4,comprises a casing of generally tubular form having its inlet passage 9at one end and its outlet passage near its other end. The outlet passage10 would be connected by pipes 10a respectively to the appropriatechambers 2, 3, 4, 5, 6 and 7, the direct connection indicated in FIGURE1 being shown only for convenience of diagrammatic illustration.

Extending across the tubular casing 8 so as to be capable of oscillatingtherein is a spindle 15 carrying a buttertly valve 16 by whichcommunication between the inlet passage 9 and the outlet passage 10 isthus controlled. The spindle 15 is provided at one of its exposed endswith a cylindrical socket 17 having its axis parallel to but displacedfrom the axis of the spindle, in which socket lies a bearing block 18which can rock in the socket and has a diametral bore through whichextends, freely but with a close working fit, a pin 19 constituting onepart of an operating lever, the pin 19 extending through oval holes inthe wall of the socket 17 so as to permit of the necessary movement. Thelever of which the pin 19 forms a part is pivoted to the casing 8 bymeans of a pivot pin 20 engaging a bearing 2-1 secured to the casing andhas a second arm 22 engaging a bore in a cylindrical bearing block 23 inthe tubular pin 13, 13a, 13b, 13C, 13d or 13e, of the valve assembly,this pin for convenience being assumed in FIGURES 2, 3 and 4 toV 4be thepin 13. The part carrying the bearing 21 is provided with a guide plate25 by which the movement of the hollow pin 13 under the action of itsassociated band 12 is controlled so that it transmits an appropriatemovement to the lever 22, 19 about its pivot pin 20.

Rigid with the casing 8 is a supporting bracket 26 having formed thereina cylindrical socket 27 having a closed inner end 28 and an open outerend facing the socket 17, as shown in FIGURE 2. The socket 27 forms aguide and partial housing for a pin 29 acted upon by a spring 30 tomaintain its end always in engagement with the socket 17 and thus applya force to the lever 19, 22 maintaining its associated band 12 intension. Thus, in FIGURE 2 as the band 12 contracts relatively to thecasing it permits the socket 17 to move to the right under the action ofthe spring-pressed pin 29 and viceversa.

The arrangement is such that increases in the mean temperature of thepart of the casing in contact with which any band 12 lies thus resultsin that band contracting relatively to (i.e. expanding less than) thecasing and openingthe associated buttery valve 16 to permit flow ofadditional cooling air through its associated cooling chamber. Theoverlap between adjacent bands, in addition, ensures that the control ofeach butterfly valve is not solely in accordance with temperaturechanges in the next adjacent cooling air chamber, with the result thatthe arrangement tends to maintain even cooling throughout the wholecircumference of the casing.

What I claim as my invention and desire to secure by Letters Patent is:

1. A turbine using hot working tluid and including a rotor, a casingsurrounding the turbine rotor and formed to provide at least one coolingair chamber extending circumferentially of said casing and having aninner wall adjacent the turbine rotor and an outer wall displacedtherefrom, means for delivering cooling air to said chamber, valve meansfor varying the flow of cooling air through said chamber, valve controlmeans located outside said outer wall and an operative connectionbetween said valve control means and said valve means, and at least onetemperature-responsive device in heat-conducting association with saidouter wall and acting on said valve control means to vary the setting ofsaid valve means in dependence upon the temperature of said outer Wall.

2. A turbine using hot working fluid and including a rotor, a casingsurrounding the turbine rotor and formed to provide a plurality ofcooling air chambers extending in series circumferentially of thecasing, each chamber having an inner wall adjacent the turbine rotor andan outer Wall radially displaced therefrom, cooling air passagescommunicating respectively with the said chambers and with a souce ofsupply of cooling air, control valves controlling the air ow through therespective cooling air passages and chambers, valve control meanslocated outside said outer wall and operatively connected to saidcontrol valves for individual control of said control valves, andtemperature-responsive devices in heat-conducting association with saidouter wall and connected to said respective valve control means, each ofsaid temperatureresponsive devices being at least in part inheat-conducting association with that section of the outer wall whichbounds the chamber through which its associated valve controls the airHow.

3. A turbine as claimed in claim 2, in which each of saidtemperature-responsive devices comprises a metallic band extending inheat-conducting contact with said outer Wall, connected at one end tosaid outer wall and connected at its other end to said valve controlmeans, said metallic band being formed of a metal having a differentco-etcient of expansion from that of said outer wall.

4. Apparatus as claimed in claim 3, in which the metallic bandsassociated with the various valve control means overlap one anothercircumferentially of the casing.

References Cited in the le of this patent UNITED STATES PATENTS2,787,440 Thompson Apr. 2, 1957 2,811,833 Broitt Nov. 5, 1957 2,858,101Alford Oct. 28, 1958 2,906,494 McCarthy et al. Sept. 29, 1959

